Hydrogen sulphide is a colorless gas, with an odor of rotten eggs. It is produced by bacterial action during the decay of both plant and animal protein and can be formed wherever elemental sulphur or certain sulphur-containing compounds come into contact with organic materials at high temperatures. In industry, it is usually an unintended byproduct, for example from the production of coke from sulphur-containing coal, from the refining of sulphur-containing crude oils, the production of disulphide, the manufacture of vicos rayon, and in the Kraft process for wood pulp.
Natural gases with high concentrations of hydrogen sulphide are known as “sour gases”. Hydrogen sulphide in sour gas and crude oil streams is separated during the “sweetening” process. The most widely used sweetening processes in the industry are the amine processes, which use a solution of water and a chemical amine to remove carbon dioxide and several sulphur compounds.
Hydrogen sulphide is also a byproduct of wastewater from treatment plants or water from agricultural practices. Additionally, hydrogen sulphide can be responsible for the unpleasant odor from liquids used in janitorial processes, RV holding tanks, portable toilets and the like. If the emission of hydrogen sulphide from these liquids can be controlled, then the unpleasant odors may be eliminated.
Hydrogen sulphide is toxic to humans and other animals, and represents a significant threat to public safety and health. It can cause serous health risks, most notably in the oil and gas, livestock, waste management and janitorial industries. At 200 parts per million, humans can no longer smell the gas, and therefore can no longer detect it by smell. Higher concentrations than this can cause nausea and headaches. At 500 to 1,000 parts per million, it causes unconsciousness, with death following in two to twenty minutes unless the victim is removed from the area of exposure immediately.
There is a need for a simple, economical and effective means of capturing hydrogen sulphide gas that is present in other gases, or in liquids.